When you are directed to “Certificate Information”, please fill out all required information:

Your Apple account email as “User Email Address”

iOS certificate distribution as “Common Name”

Then you tick on “Saved to disk”. Next, you save this file as “iOS_Distribution” and now you get an iOS-Distribution file.

Come back to your account on developer.apple.com, click on “Choose file” to upload the iOS_Distribution file you have just created. Then, click on “Continue”.

After that, double click on the file you have just downloaded and open “Keychain Access”. Now you find “iPhone Distribution” and “iOS Certificate” and export these 2 items. Then, save this file as “iOS Distribution”. Please note that the file format is (.p12)

The system will require you to set a password for the file you have just downloaded. This step is compulsory to set the file’s security.

You also have to type password which is password of your Mac and tick on “Always Allow”

When you complete these steps, you will get an iOS distribution file (or Developer’s Certificate or P12 file).